Jointed mechanism, chiefly adapted for use upon undercarriages of aircraft



May 6 1941 J. MERCIER 2,241,213

JOINTED MECHANISM, CHIEFLY ADAPTED FOR USE UPON UDERCAHRIAGES OF AIRCRAFT Filed Feb. 9, 1938 2 Sheets-Sheet 2 zxczll.

Jean Mercier INVENTOR BY W ` s ATTORNEY Patented May 6, 1941 1 UNITED STATI-:s RAT-ENT jolilclf. 2,241,213

.topman ivmcnsmsM, Cammy narran Fon Usa UroN UNnEnoaanIAGns 'or AIRCRAFT Jean Mercier, Neuilly-sur-Seine, France Application February 9, 193s, serial m1239526 In Belgium February 13, 1937 i 6 Claims.

The present invention relates to jointed mechanisms as are chiefly adapted for use as pivoted frames or struts upon retractable undercarriages of aircraft or the like.

According to an essential feature of the invention, the mechanism includes a jack which is mounted on the jointed device and controls the deformations thereof, and consists of three or more members pivotally connected together about at least two axes, the said j ack controlling, by direct action, the relative 'movements of at least two of said pivoted members.

Further characteristics will result from the following description.

I'he accompanying drawings, given merely by way of example, illustrate various embodiments of the mechanism according to the invention.

Fig. 1 shows in ...elevation a pivoted frame or pivoted frame or strut of va retractable undercarriage for aircraft or the like', comprises three members I, 2 and 3, juxtaposed to one another and pivotally connected together. Members I and 3 lare pivoted to the Vcentral member at the two ends 'I'he length of the appendages 9 and I2 lisso j chosen as to provide for a suitable leveragefor the transmission of the force supplied by the Jaw.

The operation of this device is quite simple:

With the mechanism unfolded and being in the position shown infull lines, if it is desired to raise strut provided with the'said mechanism, in which the operating jack is interposed between two nonadjacent members oi the mechanism;

Fig. 2 is a similar view of a modification in" which the operating Jack is mounted uponj one of the movable members of the mechanism;

Fig. 3 shows in elevation a strut similar to that of Fig. 1, provided with a folding and locking device; Fig. 4 shows in elevation a pivoted frame similar to that of Fig. 2, provided with a shock-absorber; Figs. 5 and 6 are elevational views, in the folded and. unfolded positions respectively. of a pivoted frame which is particularly adapted for use in the wing of aircraft and which has a relatively reduced height in the folded state;

Fig. 7 is an elevational view of a special locking device:

Fig. 8 shows in elevation another modiiication of said strut;

Figs. 9 and 10 are respectively diagrammatic elevational and plan views showing the mounting of a mechanism according to the invention, upon a retractable undercarriage, Fig. 9 showing the mechanism in the unfolded position, and Fig. 10

or central, member 2. `Members I Vanci'1-are con. v

nected together by a rod or link I3 which'is pivotally mounted on said members at' I4 Aand III. respectively.

Jack 6 is pivoted at I6 to member I, i. e., its cylinder is rotatable about point I6. Piston rod 'I is pivoted at B to the intermediate member, 2.

The operation of this device is as follows: When iiuid is admitted into jack 6 and moves the piston in the direction of the arrowv f1, member I will pivotlupwardly about point 4, under the effect of the reaction due to the thrust exerted by the piston upon member 2. ,Member I thus turns through an angle of about 90 and comes to I' (position shown inl dotted lines) On the other hand, member 3 is turned by link I3, which now comes to I3', which link, during its movement, pulls member 3 in the direction' of arrow f2, thus causing said member to pivot about point 5 and bringing it to position 3'. Thus the whole arrangemenuwhen folded up, will finally occupy the position shown in dotted lines.

'I'his disposition provides for anautomatic lock'-A ing of the members in the unfolded position.

In fact, it is necessary that,` when unfolded, an upward movement of member I, i. e., in the direction ofthe arrow, should not take place, and espe.

movement of member I. In order to prevent any such movement, the points 4, I4 and vI5 are located in such position lthat the upward movement of member 3 (f2) will tend to cause the deformation of the device by bringing it into neutral position, i. by bringing the points 4, I4 and I5 into line.

This result is obtained by placing the `point I4 above the point 4, so that an upward movement of the member 3 will tend to lower the point I4. It should be noted that this locking is not reversible, as the direct action of the jack 6 will apply at I4 a force which is practically perpendicular or very oblique to the broken line 4--I4-I5, and

this is sufiicient to cause the deformation of the device. 1 f

Fig. 3 relates to an arrangement resembling the one shown in Fig. 1, provided with an elastic reaction device consisting of a strong spring I'I, for instance, which is stretched between the members I and 2. The points I8 and I9 at whichv are in line. In the unfolded position, the length of the spring I'I is only IBL-I9', whilst its length at the dead centre is I8'-I9" and is now appreciably greater. It will thus be noted'that any unnecessary movement of the members I or 3 will only bring the device near the dead centre, and hence this constitutes a very simple automatic locking arrangement.

It is evidently possible to employ a locking device of quite a different type, such as that shown by Fig. 7. In this case the locking device comprises two catches 20 and 2l which are pivoted at 22 and are acted'upon by two respective jacks 23 and 24 mounted on member 2. These catches engage in suitable recesses formed in members I and 2., These jacks are preferably actuated at the same time as the main jack 6, and

vthey provide for the locking of the jointed device when this latter is unfolded.

Fig. 4 shows a device similar to that of Fig. 2. but which further comprises a shock-absorberv inserted between members I and 3 and consisting of a. piston 25 movable in a cylinder 2G containing air. This cylinder is pivoted to member -5, and the piston rod is pivoted to member I. The shock-absorber serves chiefly to compensate the errors in the alignment of the device, and it also serves as a means for locking the device in the position of alignment.

Figs. 'and 6 show a modification which is use chiey when it is desired to reduce the height of the device when it is folded in the wing of the aeroplane. In this case, two adjacent members are movable with respect to one of the end members.

In the case of Fig; 5, the central member has been replaced by 'jack 6 and link I3, which move together with member 3, with reference to member I, and take the position shown in Fig. 6. All of these members can be so constructed that the actual height of the members, in the folded position, will not exceed a predetermined value.

Fig. 8 shows another modcation, in which jack 6 has its cylinder, pivoted at I I, upon central member 2, and acts directly upon member I through lts piston rod 1. Member 3 is actuated, as before, by link I3, which is pivoted at I4 and I5.

l v'cially that it should not cause a corresponding Figs. 9 and 10 show an example of application of the mechanism according to the invention to the retractable undercarriage of an aeroplane. Fig. 9 is a view of the mechanism in the unfolded position. In this case, member I is pivoted at 21 to the wing 28 of an aeroplane, and member'3 is pivoted at 29 to a strut 30 carrying a wheel 3|, while being also pivoted to the wing at 32. It will be readily observed that when the jack 6 is operated, the whole mechanism will be deformed, and will now take the position shown in Fig. 10.

In the case of Fig. l1, the jack a6 is mounted on the central member 2 which is pivoted at 4 and 5 6, or by a single piston (see lalso Fig. 12) or by" any other means.

The set of links to which rod 'I is pivoted, comprises a bar or link 33 which is pivoted atl 8 to rod 1, and at 34 to a second link 35 whose other end is pivoted at 36 to member I. At a' point 3l on link 33, which may be located between the above mentioned points 8 and 34, is pivoted a rod 38 which is pivoted at its other end to a point 39 of the member 2.

Member I is further provided with a catch 4|! which is pivoted at a stationary point 4I and which is actuated at its other end 42 by a small jack 43 or thelike. When member 2 is brought to position 2 (which position is shown by the dotted lines) the catch engages a hook 44 provided upon member 2.

The fluid is supplied vto the jack cylinder at 45 or at 46, according as it is desired to unfold or to fold up the structure. The set oi links. actuating the jointed device is arranged 'in a similar mannen'and it comprises links of the same kind, which are indicated by like reference numerals provided with a digit a.

The operation of the device according to Fig. 11 is as follows: When it is desired to bring the pivoted frame herein represented from its folded position (which position, in the case of an aeroplane, corresponds to the retracted position) into the unfolded or landing position, the jack is supplied with fluid at 45, thus moving the pistons respectively in the direction of the arrows f1 and F. This displacement of the pistons will bring the pivoting points 8-34-31 of bars 33-35-38 to points 8-34-31, and said bars will be brought to 33'-3538, respectively. Thus member 2 will take position 2', which is shown by the dotted lines in Fig. 11. The links 33a-35a--3iit are moved simultaneously and in the same manner by rod 1a, thus bringing member 3 into line with the members and 2. Catches 40-4Da, which are preferably urged bysprings or by like means, will engage hooks 44--44, thus holding the frame members 2 and 3 in their respective' positionsv 2 3', so that they will maintain said frame in the unfolded position and vwill maintain the undercarriage in the operative position.

In order to fold back the frame, the uid is supplied to the jack through orices 46--46, 'thus .acting upon both sides of the pistons, and the points 42-42a ofthe said catches, respectively, thus turning these latter and releasing lthem from the jrespective hooks 44-44. This release may also be eifected automatically if jacks'43--43 are 1 upon the said pistons.

It is evident that additional locking means may K be provided forsecuring the folded members, i. e., the undercarriage, in the retracted position.

Length of the bars 33-35-38 and :dl-35- 38 as well as the distance between joints 39-31 and 36-34-8 (39--3'1ab and anus-8*) may be suitably determined-according to4 the Ac'onditions prevailing i'or each case of utilization, and chiefly in such way that the leverage shall be suilicient forthe purpose. It is preferable (to employ an arrangement such that the forces required to fold or unfold the frame shall be maximum when the resistances to be overcome are also maximum. In the folded position, bars IBL-35 (38e-35a), on the contrary to what is shown in the drawings, may have a position in which they are not parallel but are inclined at any suitable angle. In the present case, it will be noted that the mechanism' never passes through dead centres, and thus it may be actuated by the controlling device in a reliable manner, in all the positions which it may assume.

leverage of the bars or rods of the mechanism,

the forces can be transmitted in any desired mannel'.

It will be observed that this aiords a device of a very simple construction and of a minimum size and weight, which will readily correspond to all conditions of use, which result had not hitherto been obtained.

In the construction shown by Fig. 12, the jack comprises a single piston which actuates the two rods 'I-`|a at the same time. 'Ihe arrangement of the jointed linksdiffers from what is shown in Fig. 11, by the fact that the links -38 are eliminated and are replaced by two joints 41--41 which form part of the member 2 and serve for the pivoting movement of f the links" -33. But in this case it is evident that the rods of the pistons 'Iv-'P'.must 'be provided with respective joints 48-48a, of the ball-and-socket, roller or other type, by which the portions of the said links which are connected at the points 8 8l of the links 33-33respectively, may follow the circular movements of the points 8 8". l

The operation of the said device is the same as that of the device shown in Fig. 11. .In .the case'of a jack having a single piston. it will be evidently necessary, as shown' in Fig. 12, to employ two sets of links operating upon the joints 4--5 in such Way that the' movement of the pisl also-shows the unfolded position ofthe frame, in

the dotted lines.

turns about a point 51"'i of'the member 2. The

point 58 is connectedt a point 58fof the mem--` ber I by a pivoted link 59.

'I'he operation of this device is very simple: When'the pistonxin the jack cylinder moves accordingto the arrow f3, the lever 50 turns in the direction of the arrow f4, thus moving the member 4 whichpivots aboutthe point 5. This movement of the lever is transmitted by the link 55 to a rocking bar 5l which` turns in the direction of the arrow f5 andi-aises the member I by means of the link 59. Thus the members I and 3 will both turn upwardly about the points 4 and 5, and hence the undercarriage will be folded back.

Obviously, the pivoted parts of the said apparatus will have such construction that they will not mutually interfere, during their respective movements. r

For this purpose, the central member may have the form of a forked bracket, in which the outer members may have a free movement. It is also feasible to bend aside the ends of the outer members in the devices shown in Figs. 1 to 10, in order to prevent any contact with the central member. On the other hand, the members which are pivoted together may be more than three in number, and in such case, it will be simply necessary to provide aseparate operating link for each additional member.

Obviously, the invention is not limited to the `embodiments herein described and represented,

which are given solely by way of example. It is feasible, for instance, without departing from the principle of the invention, to utilize any suitable locking devices, which may or may not be aifected bythe forces causing the movement of the pivoted parts of the frame. 'I'he pivoted parts of the frame may be solid or hollow, and ln certain cases, may comprise a suitable place for attaching the jacks or like devices. It should be remarked that it will'be of no great importance if one of the members of tthe pivoted frame should be -stationary and should for instance form part of the body of the aeroplane.

comprising a folding strut member consisting of at least three main practically equivalent pivoted elements pivotally interconnected, having` substantially similar dimensions and adapted to be in alignment upon ,the unfolding of the mechanism, and a single member such as a jack mounted on said mechanism for controlling the movements thereof, said member being connected to at least two of said main elements and producing their relative displacement.

2. A mechanism according to claim 1, wherein said member is a jack comprising apiston and a cylinder, is situated between two nonadjacent elements, and is independent of the third element, the piston rod of 'the jack being pivoted In the device shown in Fig. 13, the mechanism comprises three members I, 2 and 2 which are pivoted together at 4 and 5. The piston of the jack 6 is pivotally mounted at 48 on the mem' 'Ihe other end 54 of the lever is pivoted by a link 55 at a point 55 of a second rocking bar 51 which to one of the said nonadjacent elements andits cylinder to the other element.

3. A mechanism according to claim 1, further comprising protruding parts provided on said jointed elements, the said jack being adapted to further feature residing in this that said jack use upon retractable undercarriages of aircraft comprising a folding strut consisting of at least three practically equivalent main pivoted elements pivotally interconnected, having substantiallysimilar dimensions, and adapted to be in alignment upon the unfolding of the mechanism, and a single member such as a Jack mounted on said mechanism for controlling the movements thereof, said jack being connected to at least two of `said main elements and controlling their relative displacements, and further 5 locking means for immobilizing the dierent elements in the unfolded position.,

6. A mechanism as claimed in claim 1, wherein one of the jointed elements is stationary and at least two adjacent elements which are in selO quence are adapted to move with respectto it.

JEAN MERCIER. 

